There is no official executor before probate and no right to deal with assets of the estate before probate.
While there is no explicit requirement to notify beneficiaries after probate and before distributing assets according to the will, it is advisable to do so.
Beneficiaries can hold the executor personally liable for mistakes made by the executor so it is best to issues before they escalate to legal action against you. Doing it in writing (eg email) is preferable so there is evidence if it is needed later.